Based on the measured data from 5 hydrological stations and 10 meteorological stations in the upper reaches of the Wei River, this study analyzed the nonstationarity of hydrological series and the suitability of changepoint detection methods in the typical ecological construction areas of the Loess Plateau within the upper reaches of theWei River. Using 6 changepoint detection methods, crosswavelet analysis, Budyko theory, and other approaches, it explored the evolutionary patterns of annual runoff and its influencing factors in the upper reaches of the Wei River from 1980 to 2018.The results show that the annual runoff in the upper reaches of the Wei River presented an insignificant decreasing trend (p＞0.05), the precipitation series showed an insignificant increasing trend (p＞0.05), while the potential evapotranspiration and temperature series exhibited significant increasing trends (p＜0.05). Among them, the runoff series and potential evapotranspiration series experienced a change point in 1993, and the precipitation series had a change point in 2012, with 10a lag between the change point of precipitation and that of runoff. The most suitable changepoint detection method for longseries runoff changes at hydrological stations in the upper reaches of the Wei River is the moving Ttest method. The contribution rates of the underlying surface, annual precipitation, and potential evapotranspiration to the runoff in the upper reaches of the Wei River were quantitatively analyzed, which were 64.60%, 37.87%, and -2.47%, respectively.The driving factors of runoff in the upper reaches of the Wei River are the comprehensive impact of climate and human activities. Changes in the underlying surface are the dominant factor affecting runoff changes in the upper reaches of the Wei River, followed by annual precipitation and potential evapotranspiration.